The invention relates to a bonding wedge for an ultrasonic bonder, in particular an aluminium thick wire bonder, with a wire guide in the form of a through-passage extending in the direction of the wire obliquely from above to the pressing face.
An electrically conductive wire can be pushed by means of such bonding wedges against a contact face of an electric or electronic component, with ultrasonic excitation, to produce a corresponding electrical connection between the wire and the contact face. The bonding wedge is connected to a so-called ultrasonic transducer which is in turn part of a reciprocating bonding head. A wire coil from which the bonding wire can be removed and a wire clip by means of which the bonding wire can be clamped during formation of the first bond and after formation of a so-called loop and a second bond are further essential parts of the bonding head.
When using bonding wedges with a wire guide in conjunction with aluminium wire, the relatively high frictional resistance as well as the abrasion of the aluminium wire in the region of the wire guide have been found to be extremely disadvantageous, with the result that loop formation is detrimentally affected even after a relatively short operating time. For this reason, the bonding wedges frequently have to be dismantled and cleaned of aluminium deposits, causing interruptions to operation. Moreover, the aluminium deposits in the region of the wire guide can also be entrained by the bonding wire and come into contact with the pressing face of the bonding wedge, resulting in the formation of inadequate bonds or contacts.
It is an object of the present invention to provide a bonding wedge of the type with a wire guide in which the above-mentioned disadvantages are reduced or substantially avoided, i.e. the frictional resistance of the aluminium wire and the abrasion thereof in the region of the wire guide are reduced to a minimum.